Concrete tendon gripping and sealing apparatus and method

ABSTRACT

Methods and devices for sealing and/or gripping concrete strengthening tendons. Some embodiments provide a method of forming a seal between an encapsulated anchor and a sheath of a tendon engaging the encapsulated anchor. Other embodiments provide a splice for forming a seal around a discontinuity in the sheath of a concrete tensioning tendon. Some embodiments provide a seal assembly for forming a seal between a tubular extension and a sheath of a tendon to protect an exposed portion of the tendon contained within the tubular extension. Some embodiments also provide a method of forming a fluid tight seal between tubular extension and a sheath of a tendon, while other embodiments provide a method of gripping the sheath of a tendon with a tubular extension to prevent the sheath from moving relative to the extension.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of prior-filed, co-pending U.S.Provisional Patent Application No. 62/110,938, filed Feb. 2, 2015, theentire contents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

The use of concrete as a building material is widely known as is itsfundamental strength is in compression and its weakness is in tension.It is very desirable in many construction applications to utilizematerials which can withstand both compressive and tensile forces. Asconcrete is typically unable to resist tensile forces, some type oftensile reinforcement must be utilized with the concrete.

Pre-stressed concrete utilizes reinforcement by high strength steelwhich is pre-stressed within the concrete thereby providing activetensile reinforcement within the concrete versus the passivereinforcement which resulted with the traditional, rebar-reinforcedconcrete. Such active reinforcement has been found to dramaticallyextend the range of applications where concrete can be used.

In a typical tendon tensioning anchor assembly used in post-tensioningoperations, a pair of anchors is used for anchoring the ends of thetendons suspended there between. In the course of installing the tendontensioning anchor assembly in a concrete structure, a hydraulic jack orthe like is attached to one of the exposed ends of the tendon forapplying a predetermined amount of tension to the tendon. When thedesired amount of tension is applied to the tendon, a wedge, threadednuts or the like, are used to capture the tendon and, as the jack isremoved from the tendon, to prevent its relaxation and hold it in itsstressed condition.

Metallic components within concrete structures may become exposed tomany corrosive elements, such as water, de-icing chemicals, sea water,salt water, brackish water, or spray from these sources. Wire cablecorrosion is a significant concern in post tension systems. If thisoccurs, and the exposed portions of the anchor suffer corrosion, thenthe anchor may become weakened due to this corrosion. The deteriorationof the anchor can cause the tendons to slip, thereby losing thecompressive effects on the structure, or the anchor can fracture. Also,tendon failure can occur due to water intrusion into the intersticesbetween the tendon and is typically concentrated at tendon ends oranchors. This can cause a premature failure of the post-tensioningsystem and a deterioration of the structure.

Tendon failure can occurs at portions of the tendon remote from theanchor if it is damaged during installation. The installation of tendonstypically occurs in a rugged construction environment where the tendonscan be damaged by equipment, careless handling and contact with varioussite hazards. When the elastomeric sheath is punctured, a water leakpath contacting the wire tendon is established. The puncture must bepatched to resist water intrusion between the sheath and tendon.

Tendon corrosion typically occurs near the post-tension anchors becausethe outer sheath is removed from the wire tendon at such locations. Toprotect the bare wire from corrosion, protective tubes are connected tothe anchor and are filled with grease or other corrosion preventativematerial. This conventional practice is demonstrated by differentpost-tension systems. Some conventional approaches attempt to create awater tight seal between portions of an encapsulated anchor and thetendon, such as shown in U.S. Pat. Nos. 5,749,185; 6,023,894; and6,883,280.

Unfortunately, these conventional systems do not prevent water intrusionin all circumstances due to tendons and their sheathing lackingdimensional integrity. Tendons can come from a wide variety ofmanufactures with large tolerances in outside diameter of the tendon andits protective sheath. Due to the wide variety of tendon dimensions fora nominal size, conventional seal arrangements designed to fit thelargest diameter tendons, lack sufficient sealing on lowest diametertendons of the same nominal thickness. Additional factors potentiallycausing seal problems include shrinkage and/or other dimensional changesof the sheath, encapsulation, sealing materials, or any combinationthereof.

A need exists for an improved post-tension system which better resistscorrosion than conventional technology. The system should be compatiblewith existing installation procedures and should resist the risk ofwater intrusion into contact with internal tendon wires.

SUMMARY OF THE INVENTION

One aspect of the invention relates to a method of sealing a tubularextension and a sheath of a concrete tensioning tendon. The methodincludes placing a seal on the sheath; moving the seal adjacent an endof the extension while the extension overlaps a portion of the sheath;and compressing the seal into engagement with the extension and thesheath with a seal activating member to seal the sheath and theextension. The method can further include coupling the seal activatingmember to a portion of the extension to retain the seal in place,wherein coupling can include threading the seal activing member onto theextension. In some embodiments, the tubular extension is part of anencapsulate anchor assembly. In other embodiments, the tubular extensionis part of a splice or patch.

Another aspect of the invention relates to a method of fixing a relativelocation of a sheath of a concrete tensioning tendon and a tubularextension of a concrete tensioning component. The method includesplacing a gripping member on the sheath; moving the gripping memberadjacent an end of the extension while the extension overlaps a portionof the sheath; and compressing the gripping member into engagement withthe extension and the sheath with a compression member to inhibitrelative movement between the sheath and the tubular extension. Themethod can further include coupling the compression member to a portionof the extension to hold the gripping member in place. In someembodiments, the tubular extension is part of an encapsulate anchorassembly. In other embodiments, the tubular extension is part of asplice or patch.

Another aspect of the invention includes a seal assembly for sealing atubular extension of a concrete stressing component and a sheath of aconcrete stressing tendon. The seal assembly includes a seal dimensionedand configured to extend around a circumference of the sheath andadapted to engage an end of the tubular extension while a portion of thesheath is contained within the tubular extension; and a seal activatingmember adapted to compress the seal into engagement with the extensionand the sheath to seal the sheath and the extension. In someembodiments, the seal includes an annular elastic member such as ano-ring, ferrule, or the like. Also, in some embodiments, the sealactivating member includes fastener, which can include a threadedfastener, and more particularly, a self-tapping nut. In someembodiments, the concrete stressing component includes an encapsulatedanchor assembly, wherein the extension is coupled to the encapsulatedanchor assembly, and wherein the seal assembly inhibits fluid fromentering a distal end of the extension relative to the encapsulatedanchor assembly. In other embodiments, the concrete stressing componentincludes a splice, wherein the tubular extension extends over exposedtendon from a first portion of sheath to a second portion of sheath.

Another aspect of the invention relates to a splice for sealing adiscontinuity in a sheath of a concrete tensioning tendon. The spliceincludes a sleeve having a first end, a second end, and a tubular bodyextending from the first end to the second end; a first seal assemblyadapted to be coupled to the first end of the sleeve and seal the firstend of the sleeve and the sheath, the first seal assembly adapted to becoupled to the first end of the sleeve and seal the second end of thesleeve and the sheath and a second seal assembly adapted to be coupledto the second end of the sleeve and seal the second end of the sleeveand the sheath. Each seal assembly includes a seal dimensioned andconfigured extend around the circumference of the sheath and adapted tosealingly engage the end of the sleeve; and a seal fixation memberadapted to compress the seal into engagement with the end of the sleeveand the sheath to seal the sheath and the end of the sleeve. Someembodiments include a split sleeve positioned between the sleeve and thesheath.

Another aspect of the invention relates to an encapsulated anchorassembly having a seal with a concrete stressing tendon sheath. Theencapsulated anchor assembly including an anchor having a bore adaptedto receive and hold a wire tendon in tension; encapsulationsubstantially surrounding the anchor to inhibit fluid from contactingthe anchor, the encapsulation having an extension defining a boresubstantially axially aligned with the anchor bore and adapted toreceive a portion of the sheath; a compressible seal adapted to engage adistal end of the extension and the sheath; and a compression memberadapted to compress the compressible seal into sealing engagement withthe distal end of the extension and the sheath. In some embodiments, thecompressible seal includes an annular elastic member axially compressedbetween the extension and the compression member to cause radialdeformation of the annular elastic member resulting in engagement withthe annular elastic member and the sheath. The annular elastic membercan include an o-ring, ferrule-shaped seal, and the like. In someembodiment, the compression member includes a nut threadedly engagedwith the extension, application of the threaded engagement causingcompression of the annular elastic member between the nut and extension.In some embodiments, the seal is provided with an annular tapered outersurface extending from a largest diameter proximate the rear portion toa smallest diameter proximate the front portion to allow the seal to bewedged between the sheath and the interior surface of the extension. Insome embodiments, the interior surface of the extension is provided withan annular tapered surface extending from a largest diameter proximatethe end of the extension to a smallest diameter inward from the end ofthe extension. In some embodiments, the interior surface of theextension is provided with at least one internally projectingcircumferential rib proximate the distal end of the extension, the ribbeing adapted to engage and compress the annular tapered surface of theferrule against the sheath.

Another aspect of the invention relates to a method of sealing anencapsulated anchor assembly and a sheath of a concrete stressing tendonengaging the encapsulated anchor. The method includes inserting thetendon into the encapsulated anchor, the encapsulated anchor having amain body portion substantially surrounding the anchor and an extensioncoupled to the main body portion and extending from the main bodyportion, the main body portion being formed from a first material andthe extension being formed from a second material, the second materialbeing substantially more compressible and flexible compared to the firstmaterial; arranging the sheath of the tendon to be in an overlappedengagement with the extension; activating a compressing member againstthe distal end of the extension; and compressing the distal end of theextension against the sheath to form a in response to activating thecompressing member. In some embodiments, the compressing member includesa threaded fastener, and wherein activating includes threading thethreaded fastener onto the distal end of the extension. In someembodiments, the threaded fastener includes a self-tapping nut having afront portion, a rear portion, and a threaded bore extending between thefront portion and the rear portion, the threaded bore having an annulartapered inner surface extending from a largest diameter proximate thefront portion to a smallest diameter proximate the rear portion, andwherein compressing includes further threading the front portion of theself-tapping nut onto the distal end of the extension resulting in theannular tapered inner surface of the bore to engage the distal end andincreasing compressive force to the distal end with each rotation of theself-tapping nut. In some embodiments, the compressing member includes aband clamp, and wherein activating includes squeezing the band clamp toincrease the diameter of the band clamp, positioning the band clamp in aposition on the extension in which the extension overlaps the sheath,releasing the band clamp in the position.

Another aspect of the invention relates to a seal assembly for sealingand providing visual indication of a sealing engagement between tubularextension of a concrete stressing component and a sheath of a concretestressing tendon. The seal assembly includes a seal dimensioned andconfigured to extend around a circumference of the sheath and adapted toengage an end of the tubular extension while a portion of the sheath iscontained within the tubular extension; and a seal activating memberadapted to compress the seal into engagement with the extension and thesheath to seal the sheath and the extension, wherein the seal activingmember has an at least translucent portion allowing visual indication ofcompression of the seal by the seal activating member.

Further aspects of the present invention, together with the organizationand operation thereof, will become apparent from the following detaileddescription of the invention when taken in conjunction with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exemplary cross-sectional view of one style of aconventional tendon.

FIG. 2 is an exemplary perspective, cross-sectional view of one style ofa conventional encapsulated anchor assembly.

FIG. 3 is an exploded perspective view of an encapsulated anchorassembly embodying aspects of the inventions.

FIG. 4 is a cross-sectional view of an encapsulated anchor assembly ofFIG. 3.

FIG. 5 is a cross-sectional view of Detail A of FIG. 4.

FIG. 6 is a cross-sectional view of an alternative embodiment to thatshown in FIG. 5.

FIG. 7 is a cross-sectional view of an alternative seal assemblyembodying aspects of the inventions.

FIG. 8 is a cross-sectional view of sheath splice assembly embodyingaspects of the inventions.

FIG. 9 is a cross-sectional view of Detail A of FIG. 7.

FIGS. 10A and 10B are cross-sectional views of an alternative sealassembly embodying aspects of the inventions.

DETAILED DESCRIPTION

Before any embodiments of the invention are explained in detail, it isto be understood that the invention is not limited in its application tothe details of construction and the arrangement of components set forthin the following description or illustrated in the following drawings.The invention is capable of other embodiments and of being practiced orof being carried out in various ways. Also, it is to be understood thatthe phraseology and terminology used herein is for the purpose ofdescription and should not be regarded as limited. The use of“including,” “comprising,” or “having” and variations thereof herein ismeant to encompass the items listed thereafter and equivalents thereofas well as additional items. The terms “mounted,” “connected,” and“coupled” are used broadly and encompass both direct and indirectmounting, connecting and coupling. Further, “connected” and “coupled”are not restricted to physical or mechanical connections or couplings,and can include electrical connections or couplings, whether direct orindirect. Finally, as described in subsequent paragraphs, the specificmechanical configurations illustrated in the drawings are intended toexemplify embodiments of the invention. Accordingly, other alternativemechanical configurations are possible, and fall within the spirit andscope of the present invention.

One aspect of the present invention relates to improved methods anddevices for preventing water intrusion (or other corrosive fluids orelements) on the corrosive core of a tendon when the jacket or sheatharound the tendon has been breached. Such breaches can occur in manylocations as noted above, and they can happen intentionally, such as atan anchor assembly, or unintentionally, such as unintentional damage tothe sheath mid-run (i.e., between anchor assemblies).

FIG. 1 illustrates a sectional view of one particular embodiment of aconventional mono-strand wire tendon 10 used in concrete stressing. Thewire tendon is formed with individual wire strands 12 about center wire14, which are positioned within a sheath 16. One or more wire strands 12are helically wrapped about center wire strand 14 and form helicalgrooves on the exterior surface of cable 10. Such helical grooves arecumulatively identified as shaped annulus 18 defining the space betweentendon 10 and the interior cylindrical surface of the sheath 16. Tendonsare available with slightly different configurations, such as more orless wires, additional sheathing, and different wire construction. Theembodiment provided is only for illustration purposes. Other tendonconstructions are envisioned for usage with the inventions disclosedherein.

Because wire strands 12 are circular in cross-section, spaces betweenadjacent wire strands 12 and center wire 14 are cumulatively identifiedas cable interior interstices 20. As shown in FIG. 1 and known in theart, annulus 18 and interstices 20 are filled with corrosion resistantmaterial 22. Grease or other suitable materials can be used as corrosionresistant material 22 to eliminate air pockets and to resist waterintrusion (or other corrosive elements) into contact with wire strands22. The corrosion resistant material can be utilized as a lubricant aswell.

FIG. 2 illustrates a conventional post-tension encapsulated anchorassembly 24 as illustrated in U.S. Pat. No. 6,883,280, which is herebyincorporated by reference for its teachings regarding encapsulatedanchor assemblies. The encapsulated anchor assembly 24 includes ananchor body 26 and an encapsulation 28 substantially surrounding thebody. The anchor body 26 is typically made from a metallic material suchas steel. However, it can be formed with a cast metal material suitablefor handling large compressive loads exerted by slips and otherfastening devices. The encapsulation 28 is typically a polymericmaterial.

The anchor body 26 can include many constructions known in the art. Asillustrated, the anchor body 26 includes a base 30 having an aperture 32extending through the base 30.

The encapsulation 28 includes an anchor body portion 34 engaged with theanchor body and cylindrical extension 36 extending from the anchor body26 to an end 38 distal from base 30. The distal end 38 is preferably atleast four inches distal from base 30, however shorter or longer lengthsare possible to satisfy the objectives of the invention. In someembodiments, such as shown in U.S. Pat. No. 6,883,280, the extension 36is integrally molded with the anchor body portion 34 of theencapsulation. In other embodiments, the extension 36 forming the sealwith the tendon can be separately coupled to the anchor assembly and beformed of one or more pieces, such as illustrated in U.S. Pat. No.6,023,894, the teachings of which are hereby incorporated by reference.

As further illustrated in FIG. 2, the inner surface of distal end 38 ispreferably circular in cross-section for contacting the exterior surfaceof the tendon 10 as the tendon 10 is inserted through the cylindricalextension 36 and the base aperture 32. A seal 40 can be positionedbetween contact end 38 and tendon 10 to restrict liquid intrusion intothe inside of cylindrical extension 36. By locating such a seal awayfrom the connection between tendon 10 and the slips, a buffer zoneresistant to fluid intrusion is created.

As illustrated, the seal 40 is located on the inner surface ofcylindrical extension 36. The seal 40 can be formed an shaped manydifferent ways, as described in U.S. Pat. No. 6,883,280, which is herebyincorporated by reference relative to the construction of the seal. Theseal 40 can include one or more rings for contacting the exteriorsurface of tendon 10 and for providing a liquid tight engagement therebetween. The ring(s) can comprise a molded feature on an inner surfaceof cylindrical extension or can comprise a separate component (o-ring)assembled with the contact end 38. The ring(s) can comprise a simplering feature or can comprise a compound shape. The ring(s) can be angledin a selected direction to facilitate insertion of the tendon 10 therethrough while resisting withdrawal of the tendon 10 from engagement.

By integrally molding extension 36 into base 30 and by reducing the sizeof shaped aperture 32, void spaces within the anchor interior aresubstantially eliminated. An integral extension 36 reduces the zone ofencapsulation proximate to engagement between slips and the tendon 10,thereby reducing the possibility of intrusion of corrosive elements intocontact with the exposed wire strands 12. Additionally, the extension 36provides an integral seal connection between base 30 and the exteriorsurface of the tendon 10. The extension 36 also permits such point ofconnection to be distal from base 30, thereby providing potentialgripping strength over a larger surface area than is possible within therelatively small surface area provided by base 30.

As noted in the Background, conventional extensions 36 with friction fitor interference fit style of seals located near or at the distal end 38of the extension can fail to provide appropriate sealing engagement orfluid penetration resistance in some situations, which is unacceptable.As discussed above, this problem is prevalent when a tendons thicknessis on the lower end of a nominal thickness.

FIG. 3 illustrates one embodiment of a seal assembly 56 contemplated bythe present invention in combination with an encapsulated anchorassembly 24. The seal assembly 56 includes a seal member 58 and a sealactivation and/or fixation member 60.

As shown in greater detail in FIGS. 4 and 5, this particular embodimentincludes a modification to the distal end 38 of the extension 36. Otherembodiments don't require this modification. As illustrated, an annularinner tapered surface 50 is included on the internal surface of thedistal end 38 of the extension 36. The taper 50 is created by varyingthe wall thickness of the distal end 38 the extension 36 to form atapered surface on the internal surface. In the illustrated embodiment,the outside surface of the extension 36 maintains a substantiallyconstant diameter while the diameter of the inner surface of theextension 36 decreases from the distal end 38 to a positional axiallydisplaced from the distal end 38 to form the taper. In otherembodiments, the taper 50 can be created as a separate piece insertedinto the extension 36.

As illustrated, the taper 50 can be linear (when viewed incross-section) or conical in shape. In some embodiments, the taper canbe slightly curved (when viewed in cross-section) either parabolic orhyperbolical in shape.

As illustrated, the taper can be positioned at the distal end 38 asillustrated, or it can start slightly inward from the distal end 38. Inthe illustrated embodiment, the length of the taper in the axialdirection stops short of the inner seal 40. In other embodiments, thetaper can extend to the seal 40. In such an embodiment, the taper couldend at the apex or radially innermost portion of the seal 40. In someembodiments, the inner seal 40 can be eliminated.

In the embodiment illustrated in FIGS. 3-5, a separate seal member 58 isprovided. The seal member 58 is shaped and dimensioned to be positionedin the annular void between the sheath 16 of the tendon 10 and the innersurface of the extension 36. Insertion of the seal member 58 between thesheath 16 and the extension 36 causes the seal member to engage thewalls of the sheath 16 and extension 36 in a sealing manner to preventor inhibit fluid intrusion between the sheath 16 and extension 36.

The seal member 58 can be made of many different materials to providethe sealing engagement discussed above. In one embodiment, the sealmember 58 is made from elastomeric material such as any rubber material,saturated or unsaturated, or other polymers having rubber-likeelasticity.

The seal member 58 can also be configured many different ways. In theillustrated embodiment, the illustrated seal member 58 can be describedas an annular seal member, or more particularly an elastomeric ferrule.In other embodiments, as described in greater details below, the sealmember 58 can be an o-ring.

As shown in the illustrated embodiment shown in FIGS. 3-5, the ferruleshaped seal member 58 includes a front portion 62 and a rear portion 64.Internally, the ferrule 58 is provided with a bore 66 having a diameterslightly greater than the diameter of the tube of the sheath 16 of thewire tendon 10. Externally, the ferrule 58 is provided with an annulartapered outer surface 68 extending from a largest diameter adjacent therear portion 64 to a smallest diameter adjacent the front portion 62.The ferrule 58 also has a shoulder 70 at the terminal rear of theferrule adapted to engage the force applying member 60 as laterdescribed in detail.

As illustrated best in FIG. 5, upon assembly, the annular tapered outersurface 68 of the ferrule 58 abuts and engages the annular tapered innersurface 50 of the extension 36. As the ferrule 58 is moved in the axialdirection into the distal end 38 of the extension 36 the annular taperedouter surface 68 of the ferrule 58 cams or wedges against the annulartapered inner surface 50 of the extension 36. The further these twoitems 68 and 50 are placed into engagement with each other, the frontportion 62 of the ferrule is deflected or wedged into engagement withthe sheath 16 of the tendon 10. Upon full insertion, the shoulder 70abuts the end of the extension 36 and the elastomeric properties of theferrule 58 place the ferrule in a sealed interference fit between theextension 36 and the sheath 16 regardless of dimension variations in theouter diameter of the sheath (within reason). Portions of the ferrule 58are wedged or compressed between the extension 36 and the sheath 16 toform a sealing engagement to inhibit fluid penetration.

In some embodiments, the ferrule 58 is forced between the extension 36and the sheath 16 with a tool dimensioned and configured to engage theshoulder and apply sufficient force to seat the shoulder 70 against theend of the extension. Such a tool could be semi-circular to extendaround the tendon 10 and engage the shoulder 70. A seating force couldbe applied to the tool and shoulder 70 with a hammer or other similardevice. In an embodiment such as this, the friction force created by theinterference fit may be sufficient to hold and maintain the fluid tightseal.

In other embodiments, such as the one illustrated in FIGS. 3-5, aseparate seal activating/fixation member 60 can be included with theseal assembly 56 in addition to the ferrule seal member 58. In theillustrated embodiment, a nut is threadedly engaged with the extension36 to active the sealing engagement discussed above and fix or hold theseal in place. The nut 60 is internally threaded 72 for threadedlymounting the nut to the extension 36.

In some embodiments, the extension 36 can be manufactured withcorresponding threads for engagement with the nut 60. However, in theillustrated embodiment, only the nut 60 is provided with self-tappingthreads 72. As the nut 60 is turned, the self-tapping threads engage theouter surface of the extension 36 and thread into the surface. The nut60 is provided with a maximum diameter bore of a sufficient dimension toreceive and engage the extension 36. The nut 60 of some embodiments,such as is illustrated, is also provided with a radially inwardlyextending shoulder 74 adapted to engage the shoulder 70 of the ferrule58, and the inner diameter of the shoulder slightly greater than thediameter of the tendon 10 sheath 16.

Externally, the nut 60 can include relatively small wrench engagingflats, relatively larger hand engaging flats, or a textured surface forhand engagement and threading. In use in the intended field, workers maybe wearing gloves and may have grease on their hands when working withthe nut 60. As such, it may be advantageous for hand threading purposesto have an external surface with one or more wings, like a wing nut.

In other embodiments, the seal activation/fixation member 60 can beother activation or fixation devices known in the art. For example,other fasteners, such as threaded fasteners or quick connect deviceslike a bayonet fitting can be utilized provide either or both functionsof activating the seal (i.e., pushing the ferrule into the space betweenthe extension 36 and the tendon 10) and fixing or securing the seal inplace. An example of a bayonet fitting can be found in U.S. Pat. No.2,736,871, the teachings of which are hereby incorporated by reference.Similarly, other quick disconnect fitting can utilized, such as thoseshown in U.S. Pat. No. 4,343,526 (Quick disconnect assembly); U.S. Pat.No. 3,120,968 (Quick disconnect coupling with ring detent); U.S. Pat.No. 3,773,360 (Snap Lock); U.S. Pat. No. 2,457,523 (Detent Mechanism);and the like, which are all hereby incorporated by reference withrespect to their teachings of fixation devices.

Proper engagement of the illustrated seal assembly 56 is accomplished bya predetermined number of revolutions of the compression nut 60 and asthe nut 60 is tightened; thus, translating the nut to the right of FIGS.4 and 5. The shoulder 74 of the nut 60 engages the shoulder 70 of theferrule 58 thereby forcing the ferrule 58 axially forwardly causing theferrule annularly tapered surface 68 to engage the annularly taperedinner surface 50 of the extension 36. As the ferrule 58 moves forwardly,the front portion 32 of the ferrule 26 begins to deform inwardly intothe sheath 16 due to the camming or wedging engagement between thesurfaces 68, 50, and 16. Due to the compression of the ferrule 58between the inner surface 50 of the extension and the sheath 16, a fluidinhibiting interface is formed between the extension 36 and the sheath16. Continued tightening of the nut 60 forces the ferrule 58 furtherforwardly and causes further deformation or compression of the frontportion 32 of the ferrule 26 inwardly into a wedge type sealingengagement with the sheath 16, forming the primary seal between thesheath 16 and extension 36. The shoulder portion 70 of the ferrule 58may also be deformed inwardly (radially) into engagement with the sheath16 due to compression between the shoulder 74 of the nut 60 and the endof the extension 36, and thereby provide further sealing. Tightening ofthe nut 60 will be discontinued upon the predetermined number of nutrotations occurring, and at this point a fluid inhibiting seal isestablished by the seal assembly 56.

Unexpectedly, additional advantageous effects of the illustratedembodiment have been identified. Particularly, it has been discoveredthat in addition to providing a fluid inhibiting seal, the illustratedembodiment of FIGS. 3-5 also grips and holds (or fixes) the sheath 16relative to the anchor assembly 24. In other words, the seal assembly 56prevents the sheath 16 from unexpectedly pulling out of engagement withthe anchor assembly 24, which is advantageous on long spans where it isdifficult to see both ends of the tendon from a single location.

Prior art references utilizing the internal seals discussed in U.S. Pat.No. 6,883,280 were touted as providing this benefit in addition toproviding a sealing, fluid tight engagement. However, in practice,dimensional tolerances of sheathing along with heavy use of lubriciousgrease for enhanced sealing causes problems with the interference fitdesign of the prior art. Occasionally, the sheath would be pulled out ofengagement with an anchor assembly while performing work at an oppositeanchor assembly (100 feet or more away). Once the sheathing is pulledout of the anchor and sealed at the opposite anchor, creating a fluidtight seal can be complex and may require substantial patching, which isnot preferred.

Unlike the prior art references relying upon a more passive interferencefit (such as seal 40 of FIG. 2), the inventions illustrated in FIGS. 3-5utilize an active compression fit via a separate compression member thatprovides significant gripping force to the sheath. In some earlyprototypes of this invention, the seal assembly 56 has formed a gripthat resisted at least 90 pounds of pulling force, which should preventinadvertent pull-out from the anchor. It is believed that materials anddimensions can be optimized to substantial increase the grippingstrength to further resist pull-out. In embodiments where grip is ofprimary importance, items such as seal assemblies and seals may bereferred to as gripping assemblies and grips or gripping members. Gripsor gripping members can be made from similar materials and components asthe seals discussed above. However, if only grip is of concern, thesematerials and components may not need to provide a fluid tightengagement.

An additional advantage of the illustrated embodiments is that the sealcan be selectively released or disengaged during installation to allowadjustments to be made without wasted materials. This is possible to dueto the threaded engagement of the nut. Since tendons are run aboutone-hundred feet or more at times, adjustments may be neededoccasionally on a construction site. Due to the threated engagements andinterference fits, the seal assembly 56 can be disengaged from theanchor assembly 24 and reset if necessary.

The embodiment discussed above and illustrated in FIGS. 3-5 provides ataper-on-taper wedge engagement between the ferrule 58 and the interiorsurface of the extension 36. This provides for a large contact areabetween the ferrule 58 and the extension 36, which creates a relativelylarge sealing and gripping engagement.

In alternative embodiments, the taper can be removed from one or more ofthe surfaces and yet provide a sufficient seal or grip. For example, theannularly tapered outer surface 68 of the ferrule 58 can be eliminatedleaving a generally constant diameter outer surface. In use of thismodified ferrule, significant portions of the ferrule can be wedged intocontact with the extension and compressed against the sheath 16 to forma sufficient fluid tight seal.

In yet another alternative embodiment, the illustrated ferrule 58 can beused with an extension 36 lacking an annularly internal tapered surface50. Rather, the inner surface could have a generally constant diameter,such as shown in FIG. 2 (with or without seal 40). In operation, thewedge shaped ferrule 58 would create sufficient contact with theextension to compress the ferrule between the sheath and the extensionto form a fluid tight seal or grip.

In yet another alternative embodiment, the illustrated ferrule 58 canengage one or more integrally molded ribs, such as item 40 of FIG. 2,instead of the annularly tapered internal surface 50 shown in FIGS. 4and 5. Engagement between the annularly tapered outer surface 68 of theferrule 58 with a least one rib would create sufficient contact tocompress the ferrule between the sheath and the rib to form a fluidtight seal. Additional ribs could create additional sealing interfaces.As shown in FIG. 6, a plurality of ribs can be sized differently to forma discontinuous tapered internal surface on the interior of theextension 36.

The embodiment illustrated in FIGS. 3-5 includes a secondary sealingsurface 40 positioned axially inward from the distal end 38 of theextension 36, as discussed above. As noted, this provides a secondaryinterference fit between projection 40 and the sheath 16. This secondarysealing surface 40 is not necessary for the seal assembly 56 (orvariations of it described herein) to properly work. As such, it can beeliminated in some embodiments.

In the illustrated embodiment of FIGS. 3-5, the extension 36 isintegrally molded with the anchor main body encapsulation 28. As such,the encapsulation material is one single material. One preferredmaterial is Low Density Polyethylene (LDPE). This material providesfavorable properties for threading the nut 60 and compressing theferrule 58 as the LDPE is fairly rigid and incompressible compared tothe elastomeric ferrule 58. This combination of material propertiesspecifically directs the compression primarily to the ferrule 58, whichforms the seal/gripping interface between the tendon 10 and theencapsulated anchor assembly 24.

In other embodiments, the extension 36 or portions thereof can be madefrom a more compressible, more elastomeric material, such aspolyurethane or the like, to allow compression of the extension(preferably near the distal end) 36 as shown in FIG. 7. In such anembodiment, the seal member 58 may be eliminated. The seal activatingmember 60 could simply compress a portion of the extension into thesheath 16 to create a water tight seal between the extension 36 and thetendon sheath 16. Preferably, the material is selected to allow aself-tapping nut to thread onto the end of the extension 36, wherein thenut has an annular tapered inner surface to apply greater compression asthe nut is further threaded into engagement. Alternatively, as discussedabove, a fitting with similar tapered inner surface but without threadscan be used to wedge or cam the end of the extension into sealedengagement with the tendon. Such fittings can many known fixationmethods to hold the fitting in place, such as detent engagements, aninterference fit between one or more projections with one or morerecesses on either the fitting or the projection. In yet anotheralternative, a fitting with a tapered inner surface (to provide greatercompression of the end of the extension with further engagement) can beprovided with a series of barbed projections, such as rings, to allowmovement in the engagement direction and resist movement via the barbsin the disengagement direction. In some embodiments, compression memberslike band clamps can also be used.

The seal assemblies described above were described primarily within thecontext of an anchor assembly 24. However, as discussed in thebackground, patches or splices in the sheath 16 may be required at anyposition outside the anchor assembly for many different reasons. Thesepatches or splices have the same requirement as encapsulated anchorassemblies to prevent fluid intrusion to the wires 12 and 14 of thetendon 10. Therefore, all of the above referenced seal assemblies can beutilized in a patch or splice 78 that utilizes a sleeve 80 (similar toextension 36) to patch openings in the sheath 16 or splice togetheradjacent sections of sheath 16 as shown in FIGS. 8 and 9. In such asituation, as illustrated, a seal assembly 56 would be used on each endof the tubular body to seal each end.

As illustrated in the embodiment shown in FIGS. 8 and 9, the patch orsplice assembly 78 includes a sleeve 80 covering the discontinuity 82 inthe sheath 16 and a seal assembly 56 coupled to each end of the sleeve80 to form a fluid tight seal between the sleeve 80 and the sheath 16 ofthe tendon 10. In some embodiments, such as the illustrated embodiment,a secondary sleeve 84 positioned inside the sleeve 80 can also beincorporated to enhance the seal as described in greater detail below.

As shown in the illustrations, the sleeve 80 has a generally tubularshaped body that extends a sufficient distance to appropriately cover orbridge a discontinuity 82 in the sheath 16 of the tendon 10. Dependingupon whether the sleeve 80 is merely covering a small puncture in thesheath 16 or substantial gap between two adjacent sections of sheathing(possibly incorrectly cut near an anchor), the length of the sleeve canvary. The diameter of the sleeve 80 can vary depending upon theapplication and/or materials utilized (discussed below). However, theinside diameter should be only slightly larger than the diameter of thesheath 16. Due to the dimensional variability of commercially availablesheaths, the diameter should be selected to accommodate the upper end ofavailable diameters for the nominal thickness of the tendon 10 used.Generally, the sleeve will have a diameter similar to known extensionsof encapsulated anchor assemblies commercially available.

Like the extension 36 of the encapsulated anchor assemblies of FIGS.1-7, the sleeve can be formed from a wide variety of materials havingdifferent material properties (i.e., rigidity, strength,compressibility, etc.) depending upon either the application or the sealassembly 56 utilized. For example, due to the seal member 58 beingincorporated in the illustrated seal assembly 56, a stronger, morerigid, and less compressible material like LDPE can be used. Thismaterial has advantages compared to other more compressible materialsdiscussed above. In particular, if the sleeve needs to be slid over arelatively long run of tendon (and sheath) to be put in place, a morerigid material like LDPE can be slid easier that softer, more elastic orrubbery materials while holding substantially tighter dimensionsrelative to the sheath engaged. In other words, if relatively rigidsleeve and a softer, more flexible sleeve have identical dimensions inclose approximation of the outside diameter of the sheath 16, thesofter, more flexible sleeve is more likely to get caught or hung up onthe sheath while being slid along the tendon from the free end of thetendon to the place of the discontinuity. However, in some embodiments,a sleeve having a more flexible and compressible material may bedesirable.

Although it is not always required, some embodiments, like theillustrated embodiment of FIGS. 8 and 9 can utilize a secondary sleeve84. The construction of the secondary sleeve 84 is quite similar to thesleeve 80 except the secondary sleeve 84 is a split sleeve. In otherwords, a split or slit extends from one end of the secondary sleeve 84to the other end of the split sleeve 84. In a preferred embodiment, theslit extents in a generally longitudinal direction from end to end.However, in other embodiments, the split can be configured differently,such as by being angled along the length, spiraled along the length, orother known ways of splitting.

The split sleeve 84 provides a few advantages over the external sleeve80. First, it does not have to be slid along the length of the tendon 10to be moved into position over the discontinuity 82 in the tendon 10.Rather, the split allows the split sleeve 84 to be opened upsufficiently to fit around the tendon 10 at the discontinuity 82 andelastically return to its original shape to substantially enclose thetendon 10. Second, due to this split arrangement, the split sleeve canprovided with an inner diameter much closer in approximation to the outdiameter of the tendon sheath 16. The split allows the split sleeve 84to absorb dimensional integrity issues of the sheath on commerciallyavailable tendons. Due to the elasticity of the split sleeve and therelatively thin wall thickness of it, the split sleeve can bedimensioned to snuggly engage the smallest diameter sheath (within anominal diameter range) by allowing the ends defined by opposite sidesof the split to overlap. When applied to the largest diameter sheath(within the same nominal diameter range), the ends defined by oppositesides of the split preferably resiliently return to a position wherethey are touching each other.

Like the outer sleeve 80, the split sleeve 84 can be made from a widevariety of materials. In one embodiment, the split sleeve 84 is madefrom LDPE for its elastic resilience, wherein when the sleeve is splitit tends to partially spool around itself or otherwise overlap in theabsence of a tendon. Other materials with similar properties can beutilized as well. In yet other embodiments, materials with differentproperties can be used as well. For example, if a more rubbery materiallacking the elastic resilience described above is used, it can beadhered in place to provide an inner sleeve. In some embodiments, asheet of material can be coupled to the tendon and wrapped around thetendon in a mating or overlapping arrangement. In yet other embodiments,tape can be continuously wrapped around the tendon in place of the splitsleeve.

In operation, it is preferred to have corrosion inhibiting material,such as grease, applied to the discontinuity 82 in the sheath 16 beforeapplying either the sleeve 80 or split sleeve 84, if applicable. Morepreferably, the corrosion inhibiting material is applied not only to theexposed wires 12 of the tendon 10, but also to the sheath 16 extendingalong the length of the splice. In embodiments that utilize the splitsleeve, it may be desirable to apply corrosion inhibiting material alongthe length of the split as well. Alternatively, the corrosion inhibitingmaterial can be applied on the entire outer surface of the split sleeveto further prevent fluid intrusion into the discontinuity.

As discussed above and shown in FIGS. 6 and 7, the splice assembly 78includes a seal assembly 56 at each end of the sleeve 80. Any of thesealing arrangements discussed above with respect to FIGS. 3-7 can beutilized in place of the seal assembly illustrated in FIGS. 8 and 9 toachieve the fluid tight seal desired over the length of the spliceassembly 78. Similarly, the seal assembly 56 illustrated in FIGS. 8 and9 can be utilized on the distal end 38 of the extension 36 of anencapsulated anchor assembly 24 to provide a fluid tight seal. Thedescription provided below is only one exemplary embodiment of a sealassembly.

In the embodiment illustrated in FIGS. 8 and 9, a separate seal member58 is provided. The seal member 58 is shaped and dimensioned to bepositioned between the end of the sleeve(s) 80 (84) and a portion of aseal activating member 60 to provide a sealing engagement between thesheath 16 of the tendon 10, the end of the sleeve(s) 80 (84), and theseal activating member 60.

The seal member 58 can be made of many different materials to providethe sealing engagement discussed above. In one embodiment, the sealmember 58 is made from elastomeric material such as any rubber material,saturated or unsaturated, or other polymers having rubber-likeelasticity and compressibility.

The seal member 58 can also be configured many different ways. In theillustrated embodiment, the illustrated seal member 58 can be describedas an annular seal member, or more particularly an o-ring. In otherembodiments, as described in greater details below, the seal member 58can be an x-ring, diaphragm, rubber washer, ferrule, tapered ferrule asdiscussed above, or other elastically deformable interface.

As further illustrated in FIGS. 8 and 9, a separate sealactivating/fixation member 60 is provided to compress the seal member 58into sealing engagement with the sheath 16. In particular, a nut is usedin the illustrated embodiment to activate the seal by compressing theo-ring and fix the seal in place via a threaded engagement.

The nut 60 is internally threaded 72 for threadedly mounting the nut tothe sleeve 80. In some embodiments, the sleeve 80 can be manufacturedwith corresponding threads for engagement with the nut 60. However, inthe illustrated embodiment, only the nut 60 is provided withself-tapping threads 72. As the nut 60 is turned, the self-tappingthreads engage the outer surface of the sleeve 80 and thread into theouter surface of the sleeve 80.

The nut 60 is provided with a maximum diameter bore of a sufficientdimension to receive and engage the sleeve 80. The nut 60 is alsoprovided with a radially inwardly extending shoulder 74 adapted toengage the o-ring 58, and the inner diameter of the shoulder slightlygreater than the diameter of the tendon 10 sheath 16. As illustrated,the shoulder of this embodiment has a fillet between the shoulder andmain body of the nut for better seating of the o-ring against the nutand direct most compression of the o-ring towards the sheath.

The illustrated nut 60 also has a flange 86. This flange 86 limits thethreading engagement of the nut 60 on the sleeve 80. In the illustratedembodiment, it can provide a benefit of preventing too much compressionon the o-ring 56. Due to the size of the illustrated inner bore of thenut 60, it may be possible for the o-ring to be compressed to a pointwhere the o-ring begins to extrude through the inner bore, which couldresult in a seal failure. In other embodiments, the inner diameter ofthe nut bore can more closely match the outer diameter of the sheath. Insuch embodiments, the flange 86 may not be necessary.

Externally, the nut 60 can include relatively small wrench engagingflats, relatively larger hand engaging flats, or a textured surface forhand engagement and threading. In use in the intended field, workers maybe wearing gloves and may have grease on their hands when working withthe nut 60. As such, it may be advantageous for hand threading purposesto have an external surface with two of more wings, like a wing nut.

In other embodiments, the seal activation/fixation member 60 can beother activation or fixation devices known in the art. For example,other fasteners, such as threaded fasteners or quick connect deviceslike a bayonet fitting can be utilized provide either or both functionsof activating the seal (i.e., compressing the o-ring into sealedengagement with the tendon 10) and fixing the seal in place. An exampleof a bayonet fitting can be found in U.S. Pat. No. 2,736,871, theteachings of which are hereby incorporated by reference. Similarly,other quick disconnect fitting can utilized, such as those shown in U.S.Pat. No. 4,343,526 (Quick disconnect assembly); U.S. Pat. No. 3,120,968(Quick disconnect coupling with ring detent); U.S. Pat. No. 3,773,360(Snap Lock); U.S. Pat. No. 2,457,523 (Detent Mechanism); and the like,which are all hereby incorporated by reference with respect to theirteachings of fixation devices.

Proper engagement of the illustrated seal assembly 56 is accomplished bya predetermined number of revolutions of the compression nut 60 and asthe nut 60 is tightened; thus, translating the nut to the right of FIG.9. The shoulder 74 of the nut 60 engages the o-ring 58 thereby forcesthe o-ring 58 against the end of the sleeve 80. As the nut 60 continuesto move forwardly, o-ring begins to be compressed between the nut 60 andthe sleeve 80. This in turn causes the o-ring to deform inwardly intothe sheath 16 as shown in FIG. 9 (flat portion of o-ring) and therebyforming a sealing relationship between the nut 60, the sleeve 80, andthe sheath 16. Tightening of the nut 60 will be discontinued upon theflange 86 of the nut 60 engaging the end of the sleeve 80, and at thispoint a fluid inhibiting seal is established by the seal assembly 56.

FIGS. 10A & 10B illustrate an alternative embodiment of a seal assembly56 contemplated by the present invention. The seal assembly 56 includesa seal member 58 and a seal activation and/or fixation member 60. Likethe seal assembly of the previous embodiments, this seal assembly 56 isadapted to engage the distal end 38 of the extension 36 of anencapsulated anchor or the end of a splice.

Like the embodiment shown in FIGS. 3-5, the illustrated seal member ofthis embodiment is a ferrule shaped seal member 58 including a frontportion 62 and a rear portion 64. Internally, the ferrule 58 is providedwith a bore having a diameter slightly greater than the diameter of thesheath 16 of the wire tendon 10. Externally, the ferrule 58 is providedwith an annular tapered outer surface 68 extending from a largestdiameter adjacent the rear portion 64 to a smallest diameter adjacentthe front portion 62. The ferrule 58 also has a shoulder 70 at theterminal rear of the ferrule adapted to engage the force applying member60 as later described in detail.

As illustrated best in FIG. 10B, upon assembly, the annular taperedouter surface 68 of the ferrule 58 abuts and engages the annular taperedinner surface 50 of the extension 36. As the ferrule 58 is moved in theaxial direction into the distal end 38 of the extension 36 the annulartapered outer surface 68 of the ferrule 58 cams or wedges against theannular tapered inner surface 50 of the extension 36. The further thesetwo items 68 and 50 are placed into engagement with each other, thefront portion 62 of the ferrule is deflected or wedged into engagementwith the sheath 16 of the tendon 10. Upon full insertion, the shoulder70 abuts the end of the extension 36 and the elastomeric properties ofthe ferrule 58 place the ferrule in a sealed interference fit betweenthe extension 36 and the sheath 16 regardless of dimension variations inthe outer diameter of the sheath (within reason). Portions of theferrule 58 are wedged or compressed between the extension 36 and thesheath 16 to form a sealing engagement to inhibit fluid penetration.

As illustrated in FIGS. 10A and 10B, a seal activating/fixation member60, such as a nut, is threadedly engaged with the extension 36 toactivate the sealing engagement discussed above and fix or hold the sealin place. The nut 60 is internally threaded 72 for threadedly mountingthe nut to the extension 36. In some embodiments, the extension 36 canbe manufactured with corresponding threads for engagement with the nut60. However, in the illustrated embodiment, only the nut 60 is providedwith self-tapping threads 72. As the nut 60 is turned, the self-tappingthreads engage the outer surface of the extension 36 and thread into thesurface. The nut 60 is provided with a maximum diameter bore of asufficient dimension to receive and engage the extension 36. The nut 60of some embodiments, such as is illustrated, is also provided with aradially inwardly extending shoulder 74 adapted to engage the shoulder70 of the ferrule 58, and the inner diameter of the shoulder slightlygreater than the diameter of the tendon 10 sheath 16.

Externally, the nut 60 can include relatively small wrench engagingflats, relatively larger hand engaging flats, or a textured surface forhand engagement and threading. In use in the intended field, workers maybe wearing gloves and may have grease on their hands when working withthe nut 60. As such, it may be advantageous for hand threading purposesto have an external surface with one or more wings, like a wing nut.

Proper engagement of the illustrated seal assembly 56 is accomplished bya predetermined number of revolutions of the compression nut 60 and asthe nut 60 is tightened; thus, translating the nut to the right of FIGS.10A and 10B. The shoulder 74 of the nut 60 engages the shoulder 70 ofthe ferrule 58 thereby forcing the ferrule 58 axially forwardly causingthe ferrule annularly tapered surface 68 to engage the annularly taperedinner surface 50 of the extension 36. As the ferrule 58 moves forwardly,the front portion 32 of the ferrule 26 begins to deform inwardly intothe sheath 16 due to the camming or wedging engagement between thesurfaces 68, 50, and 16. Due to the compression of the ferrule 58between the inner surface 50 of the extension and the sheath 16, a fluidinhibiting interface is formed between the extension 36 and the sheath16. Continued tightening of the nut 60 forces the ferrule 58 furtherforwardly and causes further deformation or compression of the frontportion 32 of the ferrule 26 inwardly into a wedge type sealingengagement with the sheath 16, forming the primary seal between thesheath 16 and extension 36. The shoulder portion 70 of the ferrule 58may also be deformed inwardly (radially) into engagement with the sheath16 due to compression between the shoulder 74 of the nut 60 and the endof the extension 36, and thereby provide further sealing. Tightening ofthe nut 60 will be discontinued upon the predetermined number of nutrotations occurring, and at this point a fluid inhibiting seal isestablished by the seal assembly 56.

Due to the forces (i.e., friction from tapping and seal compression)exerted on the nut 60, it may be difficult with some embodiments todetermine if the nut has rotated sufficiently to generate a proper seal.As such, the seal assembly 56 of this embodiment provides a visualindicator of proper engagement. As described in greater detail below,the visual indicator of the illustrated embodiment is on the sealactivation and/or fixation member 60.

As shown in FIGS. 10A and 10B, the seal activation and/or fixationmember 60 of this embodiment includes a seal indicator 60B. In theillustrated embodiment, the seal indicator 60B comprises a portion withat least translucent material adjacent the end of the nut 60. As usedherein, the term “at least translucent” means transmitting and diffusinglight so that objects can at least partially be viewed, which caninclude transparent within the meaning. In other words, this definitiondoes not include opaque, which blocks the passage of light. Thetranslucent material provides visual indication of proper sealingengagement when the shoulder 70 of the ferrule 58 is properly engaged bythe shoulder 74 of the nut. Through the use of translucent materials onat least a portion of this area of the nut, visual indication can beprovided when the shoulders 74, 70 are properly positioned.

In some embodiments, the portion of at least translucent material 60B isa window molded into either the axially extending portion of the sealshoulder engaging area of the nut or the radially extending portion ofthe seal shoulder engaging area. The window should be at leasttranslucent. However, in some embodiments, it can also be made ofgenerally transparent materials.

In the illustrated embodiment, the visual indication is provided bymolding the entire shoulder engaging area of the nut 60 from a singlematerial that is at least translucent. Depending upon the choice ofmaterial used, this area can be made generally transparent if desired.In some embodiments, such as the illustrated embodiment of FIGS. 10A and10B, the threaded area 60A of the nut 60 is also modeled from the sameat least translucent material. However, in other embodiments, thethreaded area 60A of the nut 60 can be made from other materials,including opaque materials.

As noted above, in some embodiments, the entire nut 60 is at leasttranslucent. In such an embodiment, the end of the seal 58 extendingbeyond tube 36 can be observed along the threaded portion 60A of the nut60 as the nut 60 is tightened and secured from the position shown in 10Ato the position shown in 10B. Once the seal 58 is viewed in the sealindicating portion 60B (FIG. 10B), one knows that the nut 60 is fullythreaded onto the tube 36 to form a proper sealing engagement.

In some embodiments, the seal 58 can be more easily seen through atranslucent body through the use of a colored seal. For example, verybright colors, such as red, orange, bright green, etc., may transmitquite well through a generally white plastic translucent nut 60. Inother embodiments, very dark seal colors, such as black or blue, mayalso transmit light (or shadows) well through certain translucentmaterials. In yet other embodiments, the seal 58 is a first color whennot sealed and a second color when sealed (i.e., under sufficientcompression by the shoulders).

The embodiments described above and illustrated in the figures arepresented by way of example only and are not intended as a limitationupon the concepts and principles of the present invention. As such, itwill be appreciated by one having ordinary skill in the art that variouschanges in the elements and their configuration and arrangement arepossible without departing from the spirit and scope of the presentinvention. For example, various alternatives to the certain features andelements of the present invention are described with reference tospecific embodiments of the present invention. With the exception offeatures, elements, and manners of operation that are mutually exclusiveof or are inconsistent with each embodiment described above, it shouldbe noted that the alternative features, elements, and manners ofoperation described with reference to one particular embodiment areapplicable to the other embodiments.

Various features of the invention are set forth in the following claims.

1.-30. (canceled)
 31. A seal assembly for sealing a tubular extension ofa concrete stressing component and a sheath of a concrete stressingtendon, the seal assembly comprising: a seal dimensioned and configuredto extend around a circumference of the sheath and adapted to engage anend of the tubular extension while a portion of the sheath is containedwithin the tubular extension; a seal activating member adapted tocompress the seal into engagement with the extension and the sheath toseal the sheath and the extension.
 32. The seal assembly of claim 31,wherein the seal includes an annular elastic member axially compressedbetween the tubular extension and the seal activating member to causeradial deformation of the annular elastic member thereby resulting insealing engagement with the annular elastic member and the sheath. 33.The seal assembly of claim 32, wherein the annular elastic memberincludes an o-ring.
 34. The seal assembly of claim 33, wherein the sealactivating member includes a nut threadedly coupled to the tubularextension to cause compression of the o-ring between the nut andextension.
 35. The seal assembly of claim 34, wherein the nut includes aself-tapping nut.
 36. The seal assembly of claim 31, wherein theconcrete stressing component includes an encapsulated anchor assembly,wherein the extension is coupled to the encapsulated anchor assembly,and wherein the seal assembly inhibits fluid from entering a distal endof the extension relative to the encapsulated anchor assembly.
 37. Theseal assembly of claim 31, wherein the concrete stressing componentincludes a splice, wherein the tubular extension extends over exposedtendon from a first portion of sheath to a second portion of sheath,wherein the seal is a first seal and the seal activating member is afirst seal activating member, and wherein the seal assembly furthercomprises: a second seal dimensioned and configured extend around thecircumference of the sheath and adapted to engage a second end of thetubular extension while a portion of the sheath is contained within thetubular extension; a second seal activating member adapted to compressthe second seal into engagement with the extension and the sheath toseal the sheath and the extension.
 38. The seal assembly of claim 32,wherein the annular elastic member includes a ferrule-shaped seal havinga front portion, a rear portion, and a bore extending from the frontportion to the rear portion, the bore being dimensioned to be receivedon the sheath, the front portion being at least partially receivableinside the extension, the seal having a shoulder at the rear portion,the shoulder of the seal being adapted to engage the seal activingmember to force the front portion of the ferrule between the sheath andthe interior surface of the extension and compress the front portionbetween the sheath and the interior surface of the extension to seal thesheath and the extension.
 39. The seal assembly of claim 38, wherein theseal activating member is operable to compress the shoulder of the sealbetween the seal activating member and an end of the extension, andwherein the seal activating member is further adapted to hold theshoulder in this compressed state.
 40. The seal assembly of claim 39,wherein the seal activating member includes a nut that threadedlyengages the extension.
 41. The seal assembly of claim 38, wherein theferrule-shaped seal is provided with an annular tapered outer surfaceextending from a largest diameter proximate the rear portion to asmallest diameter proximate the front portion to allow the seal to bewedged between the sheath and the interior surface of the extension. 42.The seal assembly of claim 41, wherein the interior surface of theextension is provided with an annular tapered surface extending from alargest diameter proximate the end of the extension to a smallestdiameter inward from the end of the extension, the annular tapered outersurface of the seal engaging the annular tapered surface of theextension in a camming manner to compress the seal and to seal thesheath and the extension.
 43. The seal assembly of claim 38, wherein theinterior surface of the extension is provided with an annular taperedsurface extending from a largest diameter proximate the end of theextension to a smallest diameter inward from the end of the extension,the annular tapered outer surface of the seal engaging the annulartapered surface of the extension in a camming manner to compress theseal and to seal the sheath and the extension.
 44. A splice for sealinga discontinuity in a sheath of a concrete tensioning tendon, the splicecomprising: a sleeve having a first end, a second end, and a tubularbody extending from the first end to the second end; a first sealassembly adapted to be coupled to the first end of the sleeve and sealthe first end of the sleeve and the sheath, the first seal assemblyincluding a first seal dimensioned and configured extend around thecircumference of the sheath and adapted to sealingly engage the firstend of the sleeve, and a first seal fixation member adapted to compressthe first seal into engagement with the first end of the sleeve and thesheath to seal the sheath and the first end of the sleeve; a second sealassembly adapted to be coupled to the second end of the sleeve and sealthe second end of the sleeve and the sheath, the second seal assemblyincluding a second seal dimensioned and configured extend around thecircumference of the sheath and adapted to sealingly engage the secondend of the sleeve; and a second seal fixation member adapted to compressthe second seal into engagement with the second end of the sleeve andthe sheath to seal the sheath and the second end of the sleeve.
 45. Thesplice of claim 44, further comprising a split sleeve positioned betweenthe sleeve and the sheath.
 46. The splice of claim 44, wherein each ofthe first seal and the second seal includes an o-ring.
 47. The splice ofclaim 46, wherein each of the first seal fixation member and the secondseal fixation member includes a threadedly engaged nut with the sleeve.48. The splice of claim 47, wherein each nut includes a self-tappingnut.
 49. The splice of claim 44, wherein each of the first seal fixationmember and the second seal fixation member includes a threadedly engagedwith the sleeve.
 50. The splice of claim 49, wherein each nut includes aself-tapping nut.
 51. The splice of claim 44, wherein each of the firstseal and the second seal include a ferrule-shaped seal. 52.-68.(canceled)
 69. A seal assembly for sealing and providing visualindication of a sealing engagement between tubular extension of aconcrete stressing component and a sheath of a concrete stressingtendon, the seal assembly comprising: a seal dimensioned and configuredto extend around a circumference of the sheath and adapted to engage anend of the tubular extension while a portion of the sheath is containedwithin the tubular extension; a seal activating member adapted tocompress the seal into engagement with the extension and the sheath toseal the sheath and the extension, wherein the seal activing member hasan at least translucent portion allowing visual indication ofcompression of the seal by the seal activating member.